From f46461e472ad14376c4d3b48074a783742bda11f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9CMalcolm?= <“mtoon@atlasprogramming.com”>
Date: Sun, 15 Dec 2024 14:11:46 -0500
Subject: [PATCH] Updates to lighting a bit

---
 platform/darwin/src/gltf/GLTFMath.cpp               | 11 +++++++++++
 platform/darwin/src/gltf/GLTFMath.hpp               |  2 ++
 platform/darwin/src/gltf/MetalRenderer+GLTFAsset.mm |  2 ++
 3 files changed, 15 insertions(+)

diff --git a/platform/darwin/src/gltf/GLTFMath.cpp b/platform/darwin/src/gltf/GLTFMath.cpp
index d7055a0360..97f5821e90 100644
--- a/platform/darwin/src/gltf/GLTFMath.cpp
+++ b/platform/darwin/src/gltf/GLTFMath.cpp
@@ -202,3 +202,14 @@ simd_float4x4 GLTFNormalMatrixFromModelMatrix(simd_float4x4 m) {
     } };
     return mout;
 }
+
+simd_double4x4 GLTFNormalMatrixFromModelMatrixD(simd_double4x4 m) {
+    simd_double3x3 nm = simd_inverse(simd_transpose(GLTFMatrixUpperLeft3x3D(m)));
+    simd_double4x4 mout = { {
+        { nm.columns[0][0], nm.columns[0][1], nm.columns[0][2], 0 },
+        { nm.columns[1][0], nm.columns[1][1], nm.columns[1][2], 0 },
+        { nm.columns[2][0], nm.columns[2][1], nm.columns[2][2], 0 },
+        {                0,                0,                0, 1 }
+    } };
+    return mout;
+}
diff --git a/platform/darwin/src/gltf/GLTFMath.hpp b/platform/darwin/src/gltf/GLTFMath.hpp
index af29606989..2882174795 100644
--- a/platform/darwin/src/gltf/GLTFMath.hpp
+++ b/platform/darwin/src/gltf/GLTFMath.hpp
@@ -130,6 +130,8 @@ simd_float3x3 GLTFTextureMatrixFromTransform(GLTFTextureTransform transform);
 
 simd_float4x4 GLTFNormalMatrixFromModelMatrix(simd_float4x4 m);
 
+simd_double4x4 GLTFNormalMatrixFromModelMatrixD(simd_double4x4 m);
+
 
 #ifdef __cplusplus
 }
diff --git a/platform/darwin/src/gltf/MetalRenderer+GLTFAsset.mm b/platform/darwin/src/gltf/MetalRenderer+GLTFAsset.mm
index c16c4f4c75..5695f386a3 100644
--- a/platform/darwin/src/gltf/MetalRenderer+GLTFAsset.mm
+++ b/platform/darwin/src/gltf/MetalRenderer+GLTFAsset.mm
@@ -372,6 +372,8 @@ simd_float3 double3_to_float3(simd_double3 input) {
             auto mvp = matrix_multiply(_projectionMatrix, model->_modelViewMatrix);
             auto mvpF = matrix_double_to_float(mvp);
             vertexUniforms.modelViewProjectionMatrix = mvpF;
+            auto normalMatrix = GLTFNormalMatrixFromModelMatrixD( model->_modelViewMatrix);
+            vertexUniforms.normalMatrix = matrix_double_to_float(normalMatrix);